Green Upconversion Emission from Er3+ Ion Doped into Sol-Gel Silica Glasses under Red Light (647.1 nm) Excitation

Abstract

Green upconversion emission from Er{sup 3+}(4f{sup 11}) ion doped into a sol-gel silica glass under red light (647.1 nm) excitation has been observed and characterized. Green and weak blue emission bands, centered at 550 and 410 nm, for the {sup 4}S{sub 3/2} {yields} {sup 4}I{sub 15/2} and {sup 2}H{sub 9/2} {yields} {sup 4}I{sub 15/2}Er{sup 3+} transitions, respectively, have been observed. These upconversion processes involve a sequential two-photon absorption. A fluorescence efficiency of 1.7 x 10{sup -6} has been estimated for the {sup 4}S{sub 3/2} {yields} {sup 4}I{sub 15/2} (550 nm) emission in Er{sup 3+} ion at room temperature for a sample doped with 1.2 mol % Er(NO{sub 3}){sub 3}. An upconversion mechanism is proposed. 24 refs., 7 figs.